Organization of Nerves that Bud from the Brain

Vocabulary practice flashcards covering the organization, origins, pathways, functions, and innervations of the twelve pairs of cranial nerves and functional divisions of the nervous system.

Central Nervous System (CNS)

The division of the nervous system consisting of the brain and spinal cord, which functions to integrate information.

Peripheral Nervous System (PNS)

The division of the nervous system composed of cranial and spinal nerves that link the CNS to the rest of the body and perform motor and sensory functions.

Somatic Sensory Division

A sensory subdivision of the PNS that carries general sensory signals from muscles, bones, joints, and the skin, as well as special sensory signals to the CNS.

Visceral Sensory Division

A sensory subdivision of the PNS that carries sensory signals from internal organs to the CNS.

Somatic Motor Division

A motor subdivision of the PNS that carries motor signals directly to skeletal muscles.

Autonomic Nervous System (ANS)

A motor subdivision of the PNS that carries involuntary signals to smooth muscle, cardiac muscle, and glands.

Sensory Nerves

Nerves that contain exclusively sensory axons that transmit information toward the CNS.

Motor Nerves

Nerves that contain exclusively motor axons that transmit information away from the CNS.

Mixed Nerves

Nerves that contain both sensory and motor axons, carrying impulses both toward and away from the CNS.

Cranial Nerves (Cerebrum Origin)

The $2$ pairs of cranial nerves that emerge from the cerebrum: CN I (Olfactory) and CN II (Optic).

Cranial Nerves (Midbrain Origin)

The $2$ pairs of cranial nerves that emerge from the midbrain: CN III (Oculomotor) and CN IV (Trochlear).

Cranial Nerves (Pons Origin)

The $4$ pairs of cranial nerves that emerge from the pons: CN V (Trigeminal), CN VI (Abducens), CN VII (Facial), and CN VIII (Vestibulocochlear).

Cranial Nerves (Medulla Oblongata Origin)

The $4$ pairs of cranial nerves that emerge from the medulla oblongata: CN IX (Glossopharyngeal), CN X (Vagus), CN XI (Accessory), and CN XII (Hypoglossal).

Olfactory Nerve (CN I)

A purely sensory cranial nerve that transmits smell (olfaction); its axons pass through the olfactory foramina of the cribriform plate of the ethmoid bone to enter the olfactory bulb.

Optic Nerve (CN II)

A purely sensory cranial nerve that transmits visual information from the eye, passes through the optic canal in the sphenoid bone, and decussates at the optic chiasma.

Oculomotor Nerve (CN III)

A motor cranial nerve passing through the superior orbital fissure that innervates the levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, and inferior oblique muscles, and provides parasympathetic innervation to the pupil and ciliary muscle.

Trochlear Nerve (CN IV)

A motor cranial nerve that exits through the superior orbital fissure of the sphenoid bone to supply motor output to the superior oblique muscle.

Abducens Nerve (CN VI)

A motor cranial nerve that passes through the superior orbital fissure of the sphenoid bone to innervate the lateral rectus muscle.

Superior Oblique Muscle

An extrinsic eye muscle innervated by CN IV (Trochlear nerve) that depresses and laterally rotates the eyeball.

Inferior Oblique Muscle

An extrinsic eye muscle innervated by CN III (Oculomotor nerve) that elevates and laterally rotates the eyeball.

Superior Rectus Muscle

An extrinsic eye muscle innervated by CN III (Oculomotor nerve) that elevates and medially rotates the eyeball.

Inferior Rectus Muscle

An extrinsic eye muscle innervated by CN III (Oculomotor nerve) that depresses and medially rotates the eyeball.

Lateral Rectus Muscle

An extrinsic eye muscle innervated by CN VI (Abducens nerve) that abducts the eyeball laterally.

Medial Rectus Muscle

An extrinsic eye muscle innervated by CN III (Oculomotor nerve) that adducts the eyeball medially.

Trigeminal Nerve (CN V)

A mixed cranial nerve with three major divisions: ophthalmic ($\text{V}_1$), maxillary ($\text{V}_2$), and mandibular ($\text{V}_3$), providing widespread sensory coverage to the face and motor control for chewing.

Ophthalmic Nerve (CN V₁)

The first branch of the trigeminal nerve; transmits sensory signals from the top of the head, forehead, and nose, passing through the superior orbital fissure and the supraorbital foramen.

Maxillary Nerve (CN V₂)

The second branch of the trigeminal nerve; transmits sensory input from the middle of the face between the eyes and the upper jaw (lips and teeth), passing through the foramen rotundum and infraorbital foramen.

Mandibular Nerve (CN V₃)

The third branch of the trigeminal nerve; carries sensory information from the lower jaw (lips, teeth) and anterior $2/3$ of the tongue (touch), and provides motor output to the muscles that elevate the jaw during chewing; passes through the foramen ovale, mandibular foramen, and mental foramen.

Facial Nerve (CN VII)

A mixed cranial nerve providing taste sensation from the anterior $2/3$ of the tongue, somatic motor control to muscles of facial expression, and parasympathetic signals to the lacrimal, submandibular, and sublingual salivary glands; travels through the internal acoustic meatus and exits the skull via the stylomastoid foramen.

Bell’s Palsy

Paralysis of facial expression muscles and partial loss of taste sensation caused by damage or inflammation to the facial nerve (CN VII) on the affected side.

Vestibulocochlear Nerve (CN VIII)

A sensory cranial nerve situated within the internal acoustic meatus of the temporal bone (does not exit the skull); consists of a vestibular branch for balance and head position and a cochlear branch for hearing.

Glossopharyngeal Nerve (CN IX)

A mixed cranial nerve exiting via the jugular foramen; transmits general sensory signals from the pharynx, tonsils, and posterior $1/3$ of the tongue, taste sensation from the posterior $1/3$ of the tongue, motor control to the stylopharyngeus muscle, and parasympathetic innervation to the parotid salivary gland.

Vagus Nerve (CN X)

A mixed cranial nerve exiting through the jugular foramen; provides taste and touch from the pharynx and larynx, visceral sensation and parasympathetic regulation to ventral body organs (heart, lungs, digestive system), and motor output to larynx and pharyngeal constrictor swallowing muscles.

Spinal Accessory Nerve (CN XI)

A motor cranial nerve arising from spinal cord rootlets ($C_1-C_5$) that exits via the jugular foramen to supply the sternocleidomastoid and trapezius muscles.

Hypoglossal Nerve (CN XII)

A motor cranial nerve exiting through the hypoglossal canal of the occipital bone to supply the intrinsic tongue muscles and extrinsic tongue muscles (genioglossus, palatoglossus, hyoglossus, styloglossus) for movement during chewing, swallowing, and speech.